Fuel oil



Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE FUEL OIL No Drawing. Application June 14, 1933, Serial 4 Claims.

This invention relates to fuel oil and to primers therefor, which are added to the fuel oil for the purpose of lowering its spontaneous ignition temperatures and/or accelerating its com- 5 bustion. Fuel 011 containing such primers finds its chief use,in connection with internal combustion engines of the Diesel type in which ignition of the fuel is effected by the heat developed in the compression of the air, and it has previously been proposed to add fuel oil for such engines. a small percentage of a. primer which explodes when rapidly heated, the temperature at which it explodes being lower than the spontaneous ignition temperature of the fuel oil itself. The beneficial action of such primers in shortening the delay period between injection of the fuel oil and its ignition, and in eliminating bumping, has already been pointed out by previous workers. I have now found that excellent primers for fuel oil are provided by compounds containing combined chlorine or bromine, and being organic or inorganic in character. Among the organic chlorides or bromides which may be mentioned are aliphatic chlorides or bromides, such as ethyl chloride, propyl bromide, dichloro ethane, tetrachloroethylene, and butyl chloride, aromatic chlorides or bromides such as bromobenzene, chloronaphthalene, and pentabromophenol, aralkyl compounds such as benzyl chloride, and alkaryl compounds such as chlorotoluene, and other compounds such as bromocamphor. Inorganic chloro or bromo compounds which may be mentiofied as illustrative are aluminium bromide and carbon tetrachloride. These substances may be added to the oil in concentrations up to about 10%, but preferably smaller amounts of the order of 1-5% are used.

My primers are also valuable as additions to oil containing large quantities of aromatic bodiw, which are characterized by high spontaneous ignition temperatures. I can thus use oils obtained by the destructive distillation or hydrogenation of coal or the like, which have 45 hitherto been of little or no value as fuel oil for internal combustion engines.

. Thus an oil fraction boiling up to 300 C., ob-

tained by the destructive hydrogenation of coal, was tested in a Moore apparatus and found to 50 have a spontaneous ignition temperature of 400 0., the delay period between injection and ignition at this temperature being three seconds. By adding 1% of pentabromophenol to theoil, the spontaneous ignition temperature was re- 55 duced to 365 C. and the delay period to 1.6 sec- In Great Britain June 15, 1932 0nd. By adding 1% of tetrachlorethylene to another sample of the oil, the spontaneous ignition temperature was reduced to 390 C. and the delay period to 2.2 seconds. By adding 1% of bromocamphor to another sample of the oil, the 5 spontaneous ignition temperature was reduced to 375 C. and the delay period to 1.6 seconds.

Certain of the substances which it has been suggested to add as primers lower the ignition temperature of the oil, but have a relatively small effect on the delay period, whilst with other substances the delay period is reduced but the ignition temperature is not lowered to the desired extent.

According to the invention I may add to the fuel oil two or more primers, one of which is selected to lower the ignition temperature and another of which is selected to reduce the delay period. For example, I add to a middle oil produced by the destructive hydrogenation of coal ethyl nitrate and benzyl bromide in roportions so as to give a mixture containing 0.5 .by weight each of these two added substances. The said middle oil has initially a spontaneous ignition temperature of 400 C. and a delay period of three seconds at this temperature (measured in an experimental apparatus of the. Moore type). The spontaneous ignition temperature of the mixture is found to be 330 C. and the delay period at 400 C. is 0.9 second. 30

If 1% of ethyl nitrate alone is added to the oil, the delay period is 0.8 second, and it is to be noted that the difierence in the delay periods of 0.8 and 0.9 second is well within the experimental error of the method employed. The spontaneous ignition temperature of the mixture when ethyl nitrate is employed alone is 365 C. When 1% of benzyl bromide is added to the oil, no ethyl nitrate being present, the spontaneous ignition temperature is 330 C. and the delay period at 400 C. is 1.5 seconds.

Other alkyl nitrates or nitrites which, like ethyl nitrate may be used to shorten the delay period are propyl nitrate, butyl nitrate and amyl nitrite.

It will be seen by comparison of these results. that when adding the same net percentage of primer, the use of two primers selected as described is much more beneficial than the use of either singly.

The above description and specific examples are illustrative only. Any modification thereof on variationvtherefrom which conforms to the spirit of the invention is included within the scope of the claims.

I claim:

1. A compression ignition fuel comprising a high boiling heavy oil of the type used as fuel tor Diesel engines, a primer selected from the class consisting of the lower alkyl nitrates and nitrites and a second primer consisting of benzyl bromide, each oi. said primers being in amounts or the order of 0.5% to 5.0% by weight of the resulting mixture.

2. A compression ignition iuel containing a middle oil obtained from the destructive hydrogenation of coal and a mixture of ethyl nitrate and benzyl bromide, each oi. said primers being in amounts of the order of 0.5% to 5.0% by weight of the resulting mixture.

- which comprises adding thereto ethyl nitrate and benzyl bromide, each 0! these ingredients being added in amounts of the order of 0.5% to 5.0% by weight of the resulting mixture.

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